Dionysus is the son of Zeus and Semele or, in some traditions, Persephone.
Zeus and Semele(most often recounted story)
Semele was a Thebian princess who Zeus slept with, as a reward Zeus said he would grant her anything. Hera found out and, disguised as Semele’s maid, convinced her to ask Zeus to show her his true form. Bound by his promise, Zeus did just that. This resulted in Semele being burned alive. Zeus had just enough time to sew Dionysus into his thigh for the rest of the baby’s term.
Zeus and Persephone(Orphic version)
Zeus decided to sleep with Persephone, who refused. He reacted by waiting for her to nap in her garden. Once she was asleep, he took the form of a snake and raped her.
After Dionysus was born he was killed by Titans when he was lured from safety by toys they offered. These toys were a mirror, ball, top, Dice or knuckle bones, a golden apple, pinecone, and withe a tuft of donkey hair or spindle. The tor him to pieces and, in turn were struck by lightning and killed.
Dionysus was them resurrected and became Thrice-Born.
Dionysus was then handed over to a group of Nymphs who dressed him as a girl to protect him from Hera. It didn’t work. Then Dionysus became a wanderer, eventually earning a place on Olympus.